EpiCompare compares epigenetic datasets for quality control and benchmarking purposes. The report consists of three sections:

  1. General Metrics: Metrics on peaks (percentage of blacklisted and non-standard peaks, and peak widths) and fragments (duplication rate) of samples.
  2. Peak Overlap: Percetnage and statistical significance of overlapping and non-overlapping peaks. Also includes upset plot.
  3. Functional Annotation: Functional annotation (ChromHMM, ChIPseeker and enrichment analysis) of peaks. Also includes peak enrichment around TSS.

Input Datasets
  • Reference peakfile: H3K9ac_EN4G38_E2_IR12
  • Total of 11 peak files:
## [1] "File1: H3K9ac_EN4G38_E1_IRpseudo1"
## [1] "File2: H3K9ac_EN4G38_E1_IRpseudo2"
## [1] "File3: H3K9ac_EN4G38_E1_IRpseudo12"
## [1] "File4: H3K9ac_EN4G38_E1_IR12"
## [1] "File5: H3K9ac_EN3G38_E1_IR12"
## [1] "File6: H3K9ac_EN3G38_E1_I1"
## [1] "File7: H3K9ac_EN3G38_E1_I12"
## [1] "File8: H3K9ac_EN4G38_E2_IRpseudo1"
## [1] "File9: H3K9ac_EN4G38_E2_IRpseudo2"
## [1] "File10: H3K9ac_EN4G38_E2_IRpseudo12"
## [1] "File11: H3K9ac_EN4G38_E2_IR12"
Code
EpiCompare(peakfiles = list(H3K9ac_EN4G38_E1_IRpseudo1, H3K9ac_EN4G38_E1_IRpseudo2, H3K9ac_EN4G38_E1_IRpseudo12, H3K9ac_EN4G38_E1_IR12, H3K9ac_EN3G38_E1_IR12, H3K9ac_EN3G38_E1_I1, H3K9ac_EN3G38_E1_I12, H3K9ac_EN4G38_E2_IRpseudo1, H3K9ac_EN4G38_E2_IRpseudo2, H3K9ac_EN4G38_E2_IRpseudo12, H3K9ac_EN4G38_E2_IR12),
           genome_build = hg38,
           blacklist = blacklist,
           picard_files = list(),
           reference = H3K9ac_EN4G38_E2_IR12,
           stat_plot = TRUE,
           chromHMM_plot = TRUE,
           chromHMM_annotation = "K562",
           chipseeker_plot = TRUE,
           enrichment_plot = TRUE,
           interact = TRUE,
           save_output = TRUE,
           output_dir = "/Users/apple/Downloads/cutandrun/ENCODE_correlation/K562_H3K9ac")

1. General Metrics

Peak Information

Column Description:

  • PeakN before tidy: Total number of peaks including those blacklisted and those in non-standard chromosomes.
  • Blacklisted peaks removed (%): Percentage of blacklisted peaks in samples. E.g. ENCODE hg19 blacklist includes regions in the hg19 genome that have anomalous and/or unstructured signals independent of the cell-line or experiment.
  • Non-standard peaks removed (%): Percentage of peaks in non-standard and/or mitochondrial chromosomes. Identified using BRGenomics::tidyChromosomes().
  • PeakN after tidy: Total number of peaks after removing those in blacklisted regions and non-standard chromosomes.

NB: EpiCompare uses filtered peakfiles (i.e. datasets after removing peaks in blacklisted regions and non-standard chromosomes)


Sample PeakN before tidy Blacklisted peaks removed (%) Non-standard peaks removed (%) PeakN after tidy
H3K9ac_EN4G38_E1_IRpseudo1 77823 0.00000 0.00000 77823
H3K9ac_EN4G38_E1_IRpseudo2 105157 0.00000 0.00000 105157
H3K9ac_EN4G38_E1_IRpseudo12 120499 0.00000 0.00000 120499
H3K9ac_EN4G38_E1_IR12 94198 0.00000 0.00000 94198
H3K9ac_EN3G38_E1_IR12 133713 0.01120 0.00972 133685
H3K9ac_EN3G38_E1_I1 178786 0.00783 0.01400 178747
H3K9ac_EN3G38_E1_I12 187696 0.00799 0.00852 187665
H3K9ac_EN4G38_E2_IRpseudo1 33747 0.00000 0.00000 33747
H3K9ac_EN4G38_E2_IRpseudo2 38899 0.00000 0.00000 38899
H3K9ac_EN4G38_E2_IRpseudo12 38252 0.00000 0.00000 38252

Fragment Information

Metrics on fragments is shown only if Picard summary is provided. See manual for help.

Column Description:

  • Mapped_Fragments: Number of mapped read pairs in the file.
  • Duplication_Rate: Percentage of mapped sequence that is marked as duplicate.
  • Unique_Fragments: Number of mapped sequence that is not marked as duplicate.



Peak widths

Distribution of peak widths in samples



2. Peak Overlap

Percentage Overlap

Percentage of overlapping peaks between samples. Hover over heatmap for percentage values.

N.B. How to interpret heatmap: [Samples in x-axis of heatmap] peaks in [Samples in y-axis of heatmap] peaks



Upset Plot

Upset plot of overlapping peaks between samples. See here on how to interpret the plot.

quartz_off_screen 2


Statistical Significance

Depending on the format of the reference file, EpiCompare outputs different plots:

  • Reference dataset has BED6+4 format (peakcalling performed with MACS2): EpiCompare generates paired boxplot per sample showing the distribution of -log10(q-value) of reference peaks that are overlapping and non-overlapping with the sample dataset.
  • Reference dataset does not have BED6+4 format: EpiCompare generates a barplot of percentage of overlapping sample peaks with the reference, coloured by statistical significance (adjusted p-value) of the overlap.

Reference peakfile: H3K9ac_EN4G38_E2_IR12

Keys:

  • Overlap: Sample peaks in Reference peaks
  • Unique: Sample peaks not in Reference peaks



3. Functional Annotation

3.1 ChromHMM

ChromHMM annotates and characterises peaks into different chromatin states. ChromHMM annotations used in EpiCompare were obtained from here.

  • Cell-type annotation file used in this analysis: K562

All samples

ChromHMM annotation of individual samples.

Overlap: Sample peaks in Reference peaks

Percentage of Sample peaks found in Reference peaks (Reference peakfile: H3K9ac_EN4G38_E2_IR12)

Percentage
H3K9ac_EN4G38_E1_IRpseudo1 33.8
H3K9ac_EN4G38_E1_IRpseudo2 34.9
H3K9ac_EN4G38_E1_IRpseudo12 29.8
H3K9ac_EN4G38_E1_IR12 28.0
H3K9ac_EN3G38_E1_IR12 25.7
H3K9ac_EN3G38_E1_I1 19.8
H3K9ac_EN3G38_E1_I12 20.9
H3K9ac_EN4G38_E2_IRpseudo1 86.4
H3K9ac_EN4G38_E2_IRpseudo2 88.4
H3K9ac_EN4G38_E2_IRpseudo12 83.9
H3K9ac_EN4G38_E2_IR12 100.0

ChromHMM annotation of sample peaks found in reference peaks.

Overlap: Reference peaks in Sample peaks

Percentage of Reference peaks found in Sample peaks (Reference peakfile: H3K9ac_EN4G38_E2_IR12)

Percentage
H3K9ac_EN4G38_E1_IRpseudo1 53.5
H3K9ac_EN4G38_E1_IRpseudo2 74.7
H3K9ac_EN4G38_E1_IRpseudo12 72.9
H3K9ac_EN4G38_E1_IR12 60.6
H3K9ac_EN3G38_E1_IR12 70.9
H3K9ac_EN3G38_E1_I1 60.7
H3K9ac_EN3G38_E1_I12 75.5
H3K9ac_EN4G38_E2_IRpseudo1 77.1
H3K9ac_EN4G38_E2_IRpseudo2 76.1
H3K9ac_EN4G38_E2_IRpseudo12 90.6
H3K9ac_EN4G38_E2_IR12 100.0

ChromHMM annotation of reference peaks found in sample peaks.

Unique: Sample peaks not in Reference peaks

Percentage of sample peaks not found in reference peaks (Reference peakfile: H3K9ac_EN4G38_E2_IR12)

Percentage
H3K9ac_EN4G38_E1_IRpseudo1 66.2
H3K9ac_EN4G38_E1_IRpseudo2 65.1
H3K9ac_EN4G38_E1_IRpseudo12 70.2
H3K9ac_EN4G38_E1_IR12 72.0
H3K9ac_EN3G38_E1_IR12 74.3
H3K9ac_EN3G38_E1_I1 80.2
H3K9ac_EN3G38_E1_I12 79.1
H3K9ac_EN4G38_E2_IRpseudo1 13.6
H3K9ac_EN4G38_E2_IRpseudo2 11.6
H3K9ac_EN4G38_E2_IRpseudo12 16.1
H3K9ac_EN4G38_E2_IR12 0.0

ChromHMM annotation of sample peaks not found in reference peaks.

Unique: Reference peaks not in Sample peaks

Percentage of reference peaks not found in sample peaks (Reference peakfile: H3K9ac_EN4G38_E2_IR12)

Percentage
H3K9ac_EN4G38_E1_IRpseudo1 46.50
H3K9ac_EN4G38_E1_IRpseudo2 25.30
H3K9ac_EN4G38_E1_IRpseudo12 27.10
H3K9ac_EN4G38_E1_IR12 39.40
H3K9ac_EN3G38_E1_IR12 29.10
H3K9ac_EN3G38_E1_I1 39.30
H3K9ac_EN3G38_E1_I12 24.50
H3K9ac_EN4G38_E2_IRpseudo1 22.90
H3K9ac_EN4G38_E2_IRpseudo2 23.90
H3K9ac_EN4G38_E2_IRpseudo12 9.38
H3K9ac_EN4G38_E2_IR12 0.00

ChromHMM annotation of reference peaks not found in sample peaks.


3.2 ChIPseeker

EpiCompare uses ChIPseeker::annotatePeak() to annotate peaks with the nearest gene and genomic regions where the peak is located. The peaks are annotated with genes taken from human genome annotations (hg19 or hg38) provided by Bioconductor.


3.3 Functional Enrichment Analysis

EpiCompare performs KEGG pathway and GO enrichment analysis using clusterProfiler. ChIPseeker::annotatePeak() is first used to assign peaks to nearest genes. Biological themes amongst the genes are identified using ontologies (KEGG and GO). The peaks are annotated with genes taken from annotations of human genome (hg19 or hg38) provided by Bioconductor.


KEGG


GO


3.4 Peak Frequency around TSS

This plots peaks that are mapping to transcriptional start sites (TSS). TSS regions are defined as the flanking sequence of the TSS sites. The frequency of peaks in downstream (-3000bp) and upstream (+3000bp) of TSS is plotted. Faint color line around the main frequency line represents the 95% confidence interval estimated by bootstrap method.

## >> Running bootstrapping for tag matrix...        2022-06-08 00时19分34秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时21分53秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时24分35秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时27分11秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时29分29秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时31分46秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时34分28秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时36分44秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时38分48秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时40分57秒 
## >> Running bootstrapping for tag matrix...        2022-06-08 00时42分57秒
## [[1]]
## [[1]][[1]]
## [[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]]
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]]
## list()
## 
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[1]][[1]][[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[1]][[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[1]][[2]]

## 
## 
## [[1]][[1]][[2]]

## 
## 
## [[1]][[2]]

## 
## 
## [[2]]

4. Session Info

## R version 4.2.0 (2022-04-22)
## Platform: x86_64-apple-darwin17.0 (64-bit)
## Running under: macOS Monterey 12.3.1
## 
## Matrix products: default
## LAPACK: /Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib
## 
## locale:
## [1] zh_CN.UTF-8/zh_CN.UTF-8/zh_CN.UTF-8/C/zh_CN.UTF-8/zh_CN.UTF-8
## 
## attached base packages:
## [1] stats4    stats     graphics  grDevices utils     datasets  methods   base     
## 
## other attached packages:
## [1] rtracklayer_1.56.0   GenomicRanges_1.48.0 GenomeInfoDb_1.32.2  IRanges_2.30.0       S4Vectors_0.34.0     BiocGenerics_0.42.0 
## [7] EpiCompare_1.0.0    
## 
## loaded via a namespace (and not attached):
##   [1] utf8_1.2.2                               tidyselect_1.1.2                         RSQLite_2.2.14                          
##   [4] AnnotationDbi_1.58.0                     htmlwidgets_1.5.4                        grid_4.2.0                              
##   [7] BiocParallel_1.30.3                      scatterpie_0.1.7                         munsell_0.5.0                           
##  [10] codetools_0.2-18                         colorspace_2.0-3                         GOSemSim_2.22.0                         
##  [13] TxDb.Hsapiens.UCSC.hg38.knownGene_3.15.0 Biobase_2.56.0                           filelock_1.0.2                          
##  [16] highr_0.9                                knitr_1.39                               rstudioapi_0.13                         
##  [19] DOSE_3.22.0                              labeling_0.4.2                           MatrixGenerics_1.8.0                    
##  [22] GenomeInfoDbData_1.2.8                   polyclip_1.10-0                          seqPattern_1.28.0                       
##  [25] bit64_4.0.5                              farver_2.1.0                             downloader_0.4                          
##  [28] vctrs_0.4.1                              treeio_1.20.0                            generics_0.1.2                          
##  [31] xfun_0.31                                BiocFileCache_2.4.0                      R6_2.5.1                                
##  [34] graphlayouts_0.8.0                       locfit_1.5-9.5                           bitops_1.0-7                            
##  [37] BRGenomics_1.8.0                         cachem_1.0.6                             fgsea_1.22.0                            
##  [40] gridGraphics_0.5-1                       DelayedArray_0.22.0                      assertthat_0.2.1                        
##  [43] vroom_1.5.7                              promises_1.2.0.1                         BiocIO_1.6.0                            
##  [46] scales_1.2.0                             ggraph_2.0.5                             enrichplot_1.16.1                       
##  [49] gtable_0.3.0                             tidygraph_1.2.1                          rlang_1.0.2                             
##  [52] genefilter_1.78.0                        splines_4.2.0                            lazyeval_0.2.2                          
##  [55] impute_1.70.0                            plyranges_1.16.0                         BiocManager_1.30.18                     
##  [58] yaml_2.3.5                               reshape2_1.4.4                           crosstalk_1.2.0                         
##  [61] GenomicFeatures_1.48.3                   httpuv_1.6.5                             qvalue_2.28.0                           
##  [64] clusterProfiler_4.4.2                    tools_4.2.0                              ggplotify_0.1.0                         
##  [67] gridBase_0.4-7                           ggplot2_3.3.6                            ellipsis_0.3.2                          
##  [70] gplots_3.1.3                             jquerylib_0.1.4                          RColorBrewer_1.1-3                      
##  [73] Rcpp_1.0.8.3                             plyr_1.8.7                               progress_1.2.2                          
##  [76] zlibbioc_1.42.0                          purrr_0.3.4                              RCurl_1.98-1.6                          
##  [79] prettyunits_1.1.1                        viridis_0.6.2                            SummarizedExperiment_1.26.1             
##  [82] ggrepel_0.9.1                            magrittr_2.0.3                           data.table_1.14.2                       
##  [85] DO.db_2.9                                matrixStats_0.62.0                       evaluate_0.15                           
##  [88] hms_1.1.1                                patchwork_1.1.1                          mime_0.12                               
##  [91] xtable_1.8-4                             XML_3.99-0.9                             gridExtra_2.3                           
##  [94] compiler_4.2.0                           biomaRt_2.52.0                           tibble_3.1.7                            
##  [97] KernSmooth_2.23-20                       crayon_1.5.1                             shadowtext_0.1.2                        
## [100] htmltools_0.5.2                          ggfun_0.0.6                              later_1.3.0                             
## [103] tzdb_0.3.0                               tidyr_1.2.0                              geneplotter_1.74.0                      
## [106] aplot_0.1.6                              DBI_1.1.2                                tweenr_1.0.2                            
## [109] ChIPseeker_1.32.0                        genomation_1.28.0                        dbplyr_2.2.0                            
## [112] MASS_7.3-57                              rappdirs_0.3.3                           boot_1.3-28                             
## [115] Matrix_1.4-1                             readr_2.1.2                              cli_3.3.0                               
## [118] parallel_4.2.0                           igraph_1.3.1                             pkgconfig_2.0.3                         
## [121] TxDb.Hsapiens.UCSC.hg19.knownGene_3.2.2  GenomicAlignments_1.32.0                 plotly_4.10.0                           
## [124] xml2_1.3.3                               ggtree_3.4.0                             annotate_1.74.0                         
## [127] bslib_0.3.1                              XVector_0.36.0                           yulab.utils_0.0.4                       
## [130] stringr_1.4.0                            digest_0.6.29                            Biostrings_2.64.0                       
## [133] rmarkdown_2.14                           fastmatch_1.1-3                          tidytree_0.3.9                          
## [136] restfulr_0.0.14                          curl_4.3.2                               shiny_1.7.1                             
## [139] Rsamtools_2.12.0                         gtools_3.9.2.1                           rjson_0.2.21                            
## [142] lifecycle_1.0.1                          nlme_3.1-157                             jsonlite_1.8.0                          
## [145] viridisLite_0.4.0                        BSgenome_1.64.0                          fansi_1.0.3                             
## [148] pillar_1.7.0                             lattice_0.20-45                          KEGGREST_1.36.0                         
## [151] fastmap_1.1.0                            httr_1.4.3                               plotrix_3.8-2                           
## [154] survival_3.3-1                           GO.db_3.15.0                             interactiveDisplayBase_1.34.0           
## [157] glue_1.6.2                               UpSetR_1.4.0                             png_0.1-7                               
## [160] BiocVersion_3.15.2                       bit_4.0.4                                sass_0.4.1                              
## [163] ggforce_0.3.3                            stringi_1.7.6                            blob_1.2.3                              
## [166] DESeq2_1.36.0                            org.Hs.eg.db_3.15.0                      AnnotationHub_3.4.0                     
## [169] caTools_1.18.2                           memoise_2.0.1                            dplyr_1.0.9                             
## [172] ape_5.6-2